Article support stand

ABSTRACT

An article support platform is resiliently mounted in the frame of an article support stand for reciprocal vertical movement in the stand in order to support a stack of articles, such as trays, dishes and the like, with the uppermost article in the stack located at a predetermined level at all times. The resilient support mechanism for the platform includes a lever which is pivotally mounted in the frame at a fixed pivot point and operatively connected to the platform by at least one flexible cable so that the lever is caused to pivot about its fixed pivot point during vertical movement of the platform. A resilient spring or the like is operatively connected between the lever and the frame to resist downward vertical movement of the platform while biasing the lever in a predetermined direction to urge the platform towards its uppermost position.

United States Patent 91 Bergenthal ARTICLE SUPPORT STAND [75] Inventor:Eckhard J. Bergenthal, Glassboro,

[73] Assignee: Caddy Corporation of America,

Pitman, NJ.

22 Filed: July 11, 1972 211 Appl. No.: 270,819

[ June 28, 1974 Primary Examiner-Bobby R. Gay Assistant Examiner-DarrellMarquette Attorney, Agent, or Firm-Curtis, Morris & Safford ABSTRACT Anarticle support platform is resiliently mounted in the frame of anarticle support stand for reciprocal vertical movement in the stand inorder to support a stack of articles, such as trays, dishes and thelike, with the uppermost article in the stack located at a predeterminedlevel at all times. The resilient support mechanism for the platformincludes a lever which is pivotally mounted in the frame at a fixedpivot point and operatively connected to the platform by at least oneflexible cable so that the lever is caused to pivot about its fixedpivot point during vertical movement of the platform. A resilient springor the like is operatively connected between the lever and the frame toresist downward vertical movement of the platform while biasing thelever in a predetermined direction to urge the platform towards itsuppermost position.

15 Claims, 8 Drawing Figures PAH-m Imam SHEET 1 UP 3 PATENIEBJUN 93820.478

SHEET 3 [IF 3 ARTICLE SUPPORT STAND The present invention relates toarticle support stands and more particularly to support stands whichwill support a stack of individual articles with the uppermost articleof the stack in a predetermined positlon.

Support stands of the above type have been previously proposed whichwill support a stack of articles, such as for example, serving trays,dishes or the like, on a resiliently mounted platform so that theuppermost article in the stack will always be located at a predeterminedlevel on the stand. Such support stands are often used in cafeterias orother establishments, i.e., hospitals, schools and the like, wherein acontinuous supply of individual trays or dishes must be present forpeople to use. Preferably, such support stands will hold a relativelytall stack of such articles and will keep the uppermost article at apredetermined height, e.g. the level of an adjacent countertop, so thatthe article is easily located and removed from the stack. After anarticle is removed, the support mechanism in the stand causes the entirestack to move upwardly slightly so that the next article in the stack ispresented at the desired location or level.

One problem which exists with previously proposed devices of this typeis that the force which is applied to the article support platform willvary over the path of travel of the platform. Thus, the platform willmove downwardly, under a given weight, a smaller distance at the top ofits path of travel, i.e., adjacent the countertop level, than it willunder the same additional weight at a lower level in its path of travel.For example, if the platform moves downwardly one inch under the load offive trays when it is near the countertop level, it often occurs thatthe platform will move down more than 1 inch when an additional fivepans are added to the stack as the platform approaches its lowermostposition in the stand. This problem is undesirable in article supportstands of this type since the number of articles which can be supportedon the stand will be reduced and the stand will not keep the uppermostarticle in the stack at'the same level at all times, irrespective of theheight of the stack. The problem arises because of the fact that thetorque which resists the downward movement of the platfonn under theload of the stack of articles or trays generally varies as the platformmoves downwardly.

Moreover, with this type of article support stand it is often necessaryto adjust the force with which downward movement of the support platformis resisted. This force must be adjusted since the articles to besupported on the stand at different times may have different weights.Thus, if the force resisting downward movement of the platform is suchthat the platform moves downwardly one inch under the weight of fivetrays, then, when a stack of articles or trays having a greater weightare placed on the stand, five of the heavier articles will move theplatform downwardly more than one inch. Accordingly, over a given pathof platform travel, less of the heavier articles can be sup ported onthe platfonn. Obviously, it therefore becomes desirable to be able toincrease the resistance force on the support platform to accommodatemore of the heavier articles. However, this has not always beencompletely or satisfactorily possible with previously proposed supportstands.

Accordingly, it is an object of the present invention to readily supporta stack of articles on a support stand wherein the uppermost article ofthe stack will be maintained at a predetermined level, with the forceresisting downward movement of the stack being constant over the entirepath of travel of the platform.

Another object of the present invention is to resiliently support astack of articles on a vertically movable platform which is biasedtowards its upward position with a constant force gradient.

Yet another object of the present invention is to provide an articlesupport stand of the described type which is relatively simple anddurable in construction and inexpensive to manufacture.

In accordance with an aspect of the present invention an article supportstand is provided having a generally vertically extending frame in whichan article support platform is mounted for reciprocal vertical movementbetween upper positions. The support platform extends horizontallyoutwardly of the frame, in the manner of a cantilever, and isresiliently supported on the platform by a resilient or spring typemechanism which biases the platform towards its uppermost position andwhich resists downward movement of the platfonn. This mechanism includesa lever which is pivotally mounted in the base of the frame for pivotalmovement about a fixed pivot point in a vertical plane. A first pair offlexible cables, respectively connected at one end to a common point onthe frame and connected at their opposite ends to opposite sides of theplatform are guided over a plurality of guide rollers mounted in theframe and a pair of rollers mounted on the lever. The latter rollersrespectively engage and reverse the direction of the cables betweentheir ends so that vertical movement of the platform between its upperand lower positions, in response to articles or stacks of articlesplaced thereon, causes the lever to pivot about its pivot point.

A spring is operatively connected to the lever to apply a biasing forceto the lever and create therewith a moment force about the levers pivotpoint which resists downward movement of the platform and normally urgesthe platfonn towards its upper position. The biasing spring force isapplied to the lever through a first carriage which is mounted forselective movement along the lever in order to vary the point at whichthe biasing force is applied thereto. In addition, a second carriagemember, which is vertically movably mounted in the frame, is operativelyconnected to the first carriage on the lever in order to vary thelocation of the carriage along the lever in response to adjustment ofthe vertical position of the second carriage. As a result, the point ofapplication of the biasing force to the lever is varied-so that themoment force resisting the vertical movement of the platform issimultaneously adjusted.

The above, and other objects, features and advantages of thepresentinvention will be described in detail with reference to the accompanyingdrawings, wherein:

movement of the actuating mechanism of the invention, and in dottedlines a second position of a portion of the lever biasing mechanism;

FIG. 3 is a sectional view taken along line 33 of FIG. 2;

FIG. 4 is a sectional view taken alone line 4-4 of FIG. 2;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2;

FIGS. 6 and 7 are partial elevational views, similar to In order tosupport articles on stand 10, a horizontally extending support platform14 is mounted at one end 16 thereof in frame 12. This platform ismounted for vertical movement between upper and lower positions,illustrated respectively in solid and phantom lines in FIG. 1, and isadapted to support a plurality of articles 18 on its upper surface 20.The articles 18 may be of any desired form and, in the illustrativeembodiment of the invention are shown as a stack of individual trayssuch as may be utilized in a cafteteria. Of course, it is to beunderstood that the articles supported on surface 20 may take anydesired form as may be required for the particular use to which thestand is placed. In any case, stand 10 is constructed so as to maintainthe uppermost article or tray in stack 18 at a predetermined level, suchas for example, at the level of the top 22 of stand frame 12. Thus,platform 14 is supported, as described hereinafter, so as to movedownwardly as additional articles are placed on stack 18 and to moveupwardly as articles are removed from the stack, thereby maintaining theuppermost article at the desired predetermined level. i

To accomplish this result, platform 14 is supported in frame 12 by apair of arms 24 which extend through vertical slots 26 in the front face28 of stand 10. As seen in FIGS. 3, 6 and 7, arms 24 each are secured toseparate support plates 29 at their free ends 30 within frame 12. Twopairs of spaced rollers 31 are mounted on each of the support plates 29and respectively receive between them generally rectangular guide tracksor tubes 32 on which the pairs of rollers 30 move during the verticalmovement of platform 14. By this arrangement, the platform is maintainedat all times in its generally horizontal position, supported generallyasa cantilever.

Platform 14 is supported in frame 12 by a resilient support mechanism34, most clearly illustrated in FIGS. 2 and 6-8 of the drawings. Thissupport mechanism biases platform 14 towards it uppermost position andresists the movement of the platform towards the base of frame 12. Thesupport mechanism is constructed so that a constant or linear forcegradient is applied to platform 14 at all times. That is, platform 14will move downwardly at substantially equal distances under a givenweight of trays at any point in its vertical movement. For example, ifthe platform moves downwardly one inch, under the weight of five traysadded to the platform when it is in its uppermost position, then theplatform will also move downwardly one inch when an additional fivetrays are added to a stack of trays when the platform is near itslowermost position. This constant gradient is achieved because, by theconstruction of the invention, the moment arm which is used to producethe torque that resists movement of platform 14 is constant at alltimes, thus there is no variation in the distance traveled by platform14 upon removal or addition of a given number of trays or other articlesfrom the stack.

Support mechanism 34 includes an elongated actuating lever 36 which ismounted on support block 38, secured in the base 40 of frame 12, forrotation about a fixed pivot point 42. Thus, at all times during the useand actuation of the apparatus lever 36 will rotate, as describedhereinafter, about the same pivot axis. This is an important feature ofthe present invention since, as a result of this construction, themoment arm which is used to produce the torque that resists downwardmovement of platform 14 is the same and will remain the sameirrespective of what position platform 14 occupies at a given moment intime.

Platform 14 is supported by lever 36 through a pair of cables 44, 46,more clearly illustrated in FIGS. 6 and 7. Cable 44 is rigidly securedat one end 48 thereof to the left arm 24 of platform 14, and extendsover a roller or pulley 50 rotatably mounted in the top of frame 12.From pulley 50 cable 44 extends to and over a roller 52 which isrotatably mounted on the free end 54 of lever 36. Roller 52 is one of abank of three rollers (see FIG. 3) rotatably mounted on the end of thelever 36 to form a portion of the completed actuating mechanism 34. Fromroller 52 the direction of cable 44 is reversed so that the cableextends back towards the arm 24 at the left of platform 14 and the freeend 56 of the cable is rigidly connected to a support block 58 or thelike secured to frame 12.

Cable 46 on the other hand, is secured at its free end 59 to the arm 24on the right side of platform 14. From this point the cable extends overa roller or pulley 60, also rotatably mounted on frame 12, towards aroller 62 which is rotatably mounted on a common axis with roller 50(see FIG. 3). From roller 62, the direction of cable 46 is reversed andthe cable extends to a roller 64 which is mounted on the free end 54 oflever 36 on a common axis with roller 52. Roller 64 again reverses thedirection of cable 46, so that the cable now extends in the samedirection as cable 44, with its free end 66 rigidly secured with the end56 of cable 44 to support block 58.

It will be appreciated that since cables 44 and 46 extend in the samedirection about rollers 52, 64, they will act simultaneously on or inresponse to lever 36. Thus, for example, when platform 24 movesdownwardly, the ends 48, 59, respectively of cables 44, 46 will movedown together and in an equal amount. Simultaneously, because cables 44and 46 extend in the same direction about rollers 52, 64 on lever 36,the lever 36 will be caused to pivot about axis 42 in a counterclockwisedirection under the influence of both of the cables. Further, when lever36 moves in a clockwise direction, under the biasing force applied toit, as more fully described hereinafter, the lever will draw cables 44and 46 simultaneously therewith, to cause the cables to lift platform 14towards its uppermost position. Further, because of the arrangement ofcables 44 and 46, the free end 54 of lever 36, and in particular, theaxis of rotation of rollers 52 and 64, will move laterally a distancewhich is equal to one half of the distance which platform 14 movesvertically. Thus, if platform 14 moves downwardly one inch, it will beseen that the one inch of extra cable which must be drawn from cables 44and 46 to permit this movement will be supplied from the two lengths ofcables which extend from rollers 52 and 64 respectively. Each of theselengths will supply one half of the needed cable length for the verticalmovement. Thus, platform 14 can move vertically twice the distance thatlever 36 moves laterally.

Actuating mechanism 34 further includes a spring 70 which is operativelyconnected to lever 36 in order to apply the desired biasing forcethereto. This spring may comprise one or more individual springs mountedin frame 12. In the illustrative embodiment of the invention a pair ofsprings 70 (see FIG. 3) are mounted with their ends 72 secured tosupport member 58 on a common axis with the ends 56, 66 of cables 44,46. The free end 74 of springs 70 are commonly connected to an elongatedflexible cable 76 which is in turn operatively connected to lever 36, onthe right side thereof, as seen in FIG. 2, in order to apply the biasingforce to lever 36.

Cable 76 is guided over a pair of rollers 78 mounted in the base 40 offrame 12, and passes over a roller 80 rotatably mounted in a carriage 82on an axis which is in generally vertical alignment with the axis of oneof the rollers 78. Carriage 82 is vertically movably mounted in frame12, to permit adjustment of the point of application of the biasingforce to lever 36, as more fully described hereinafter. From roller 80,cable 76 extends .toward lever 36 and over a roller 84 which reversesthe direction of the cable. The free end 86 of cable 76 is then securedto the carriage 82.

Roller 84 is rotatably mounted on a carriage 88 which is, in turn,slidably mounted on lever 36 so that its position along the lever may beadjusted. In this manner, it is seen that the spring force provided byspring 70 is applied to lever 36 through cable 76 and roller 84. Thisforce produces a moment force about pivot point 42 which normally biaseslever 36 in a clockwise position, i.e., into the solid line positionillustrated in FIG. 2. When any weight, or a stack of trays 18, isplaced on platform 14, the platform tends to move downwardly against theresistance of this force. The weight on platform 14 causes cables 44, 46to urge the free end 54 of lever 36 in a counterclockwise directionagainst the bias force of spring 70. On the other hand, when articlesare removed from platform 14, the bias force of spring 70 will urge thelever arm 36 towards the right, in a clockwise direction, to raiseplatform 14 in order to maintain the uppermost tray or article in thestack at the desired predetermined level. It should be noted thatbecause of the pivotal mounting of lever 36 about the fixed pivot point42, the torque produced by arm 36 varies linearly since the moment armproduced by lever 36 is constant throughout the entire movement of lever36 between its extreme positions, illustrated in solid and phantom linesin FIG. 2, because the point of application of the spring force to thelever is fixed. Accordingly, there is a constantly linear force gradientapplied to platform 14 throughout its path of travel so that a givenweight applied or removed from platform 14 will cause the platform tomove a fixed distance, irrespective of the location of the platform whenthe weight is added or removed therefrom.

Carriage 88 comprises a pair of spaced plates 94 (FIG. 5) which receivetherebetween the lever 36. Plates 94 are interconnected by a pair ofrollers 96, which are mounted thereon in spaced relation to each other(FIGS. 2 and 5) and are held in relatively fixed position with respectto each other and to rollers 96 by the nuts 98 which are secured to thefree ends of the roller shafts 100. Roller 84 is rotatably mountedbetween plates 94 on the side of lever 36 opposite rollers 96, so thatas a result of this arrangement, the bias force applied to carriage 88by spring 70, through cable 76, holds rollers 96 against the backsurface 102 of lever 36 and permits the carriage 88 to move along thelever. The position of carriage 88, along lever 36, is adjusted by meansof a reference cable which is operatively connected between carriage 88and the vertically movable carriage 82. Cable 90 extends from its end 92secured to carriage 88, along the rear side 102 of lever 36 and itsdirection is reversed by the passage of the cable over a roller 104(FIG. 3) which is rotatably mounted on a common axis with roller 52, 64at the free end of lever 36. Cable 90 then extends along the front, orright, surface of lever 36 between plates 94 of carriage 88 and over anadditional roller 106 rotatably mounted in any convenient manner on thepivot axis 42 with lever 36. From this point the direction of the cableis again changed by passage over roller 106 and it is guided to a roller108 rotatably mounted in the base 40 of frame 12 and thence to carriage82 where its end 110 is rigidly secured on the same axis 112 as the end86 of cable 76.

By this arrangement, it will be appreciated that vertical movement ofcarriage 82 will cause movement of carriage 88 along lever 36. Thismovement will be in a one to one relationship because of the mountingarrangement' of cable 90, so that if carriage 82 moves upwardly one inchfrom its solid line position, carriage 88 will move along lever 36 oneinch. This movement is shown in dotted lines in FIG. 2. As can be seentherein, when carriage 88 is moved upwardly along lever 36, the roller84 moves closer to carriage 82. This lateral movement of roller 84 doesnot effect spring 70, because of the arrangement of cable 76 aboutrollers 80 and 84 on the respective carriages. As will be appreciatedfrom a careful consideration of the drawing, when roller 84 moves to theright, the excess cable which is present because of this movement isaccommodated by the upward movement of roller 80 in carriage 82 so thatthe excess cable permits roller 80 to move upwardly without pulling onspring 70. As a result of this construction, the location of theapplication of the bias force applied by spring 70 to lever 36 may beadjusted. Therefore, the moment force applied by lever 36 to rollers 52,64 and thus cables 44, 46 can be varied as desired in order toaccommodate articles on platform 14 of varying weights.

In the operation of the device, the tension in cable 76 is initiallyadjusted by a conventional threaded adjustment connection 114 in orderto exactly counterbalance the weight of platform 14 when it is empty. Inthis manner spring 70 is initially preloaded. By the construction ofcarriages 88 and 82, this preloaded condition is not effected whencarriage 88 is adjusted along lever 36 since the position of connection114 with spring 70 is not effected by the movement of the carriages orof rollers 84 and 80.

The construction of carriage 82 is illustrated most clearly in FIG. 4 ofthe drawing. As seen therein, this carriage comprises a pair of sideplate members 116 between which roller 80 is rotatably mounted in anyconvenient manner. Two pairs of guide rollers 118 are mounted on plates116 in spaced parallel relation to each other. These rollers arepositioned to engage a pair of vertically extending rigid frame members120 and to ride thereon during vertical movement of the carriage.Because spring 70 creates a tension in cable 76 which, at point 86 pullscarriage 82 towards the left in the drawing, rollers 118 are constantlymaintained in engagement with frame members 120.

Vertical adjustment of carriage 82 is achieved by the use of hollowsleeve 122 rigidly secured to the upper end 124 of plates 116. Sleeve124 includes a threaded nut or the like 126 rigidly secured to the upperend thereof which threadedly receives an elongated rod 128 extendingbetween frame members 120 and through a support block 130 rigidlyconnected to these frame members. The upper end 132 of rod 128 isrigidly secured to a circular bearing block 134 which is seated onbearings 136 to permit rod 128 to be rotated but to prevent it frommoving downwardly in the frame 12.

The free end 132 of rod 128 can be provided with any convenient engagingmechanism which will permit rotation of the rod in nut 126. In theillustrative embodiment of the invention end 132 is provided with a slot138 which extends through the top surface 22 of frame 12 and which canbe engaged by a screw driver or the like to rotate rod 128. Uponrotation of this rod, sleeve 122 is moved upwardly or downwardly alongthe rod depending upon the direction of rotation thereof. This movementof sleeve 122 in turn causes carriage 82 to move upwardly or downwardlyalong the track provided by frame members 120. As described above, thismovement of carriage 82 causes, through reference cable 90, simultaneousmovement of carriage 88 along lever 36 in order to adjust the momentforce applied by the lever.

Accordingly, it is seen that a relatively simple and inexpensivelyconstructed article supporting stand is provided which will movablysupport a stack of articles in order to maintain the uppermost articlein the stack at a predetermined level. Initially, the apparatus is setby the adjustment of cable 76 through connecting member 114 on spring 70in order to preload the spring to exactly counterbalance the weight ofplatform 14. Thereafter, carriage 82, and thus carriage 88, is adjustedin order to provide a predetermined moment force on rol-, lers 52, 64and thus cables 44, 46, in order to permit the platform 14 to movedownwardly a predetermined distance for a predetermined weight. Forexample, if it is desired that the platform move down 1 inch under theload or weight of five trays, the carriage 82 is moved to a positionwhich will permit this deflection of platform 14 under that weight. Oncethis adjustment is made, that deflection or weight to distance gradientwill be constant throughout the entire range of movement of platform 14and lever 36 because of the fact that the lever am is pivoted about thefixed pivot point 42 so as to have a constant moment arm. Of course, inaccordance with Hookes law, the bias force applied by spring 70 to thecarriage 88 is constantly linear through the intire arc of movement oflever 36. Since the spring is expanded along a straight. line. Sincethis distance and the force provided by spring are constant, the momentforce produced by the lever is also constant.

Should it be desired at a later time to vary the force gradient topermit greater or lesser deflection under a given load, the positioncarriage 82 and thus carriage 88 can again be adjusted in order toachieve the desired gradient. This adjustment of the carriage in no wayeffects the preload on spring 70, since the roller 84 moves towardscarriage 82 to permit the carriage to move upwardly without effectingthe deflection of spring 70. This is also an important feature of theinvention since, as a result, the platform 14 will be exactlycounterbalanced at any setting of carriage 82 so that it will alwaysreturn to its uppermost position when no articles are placed on itsupper surface.

Although an illustrative embodiment of the present invention has beendescribed herein with reference to the accompanying drawings, it is tobe understood that various changes and modifications may be effectedtherein by one skilled in the art without departing from the scope orspirit of this invention.

What is claimed is:

1. An article support stand comprising, a frame, a generally horizontalarticle support platform mounted on said frame for reciprocal verticalmovement, said means including a lever pivotally mounted in said frameat a fixed pivot point, means operatively connected between said lever,frame and platform, for causing said lever to pivot about said fixedpivot point during vertical movement of said platform and resilientmeans mounted in said frame for extension is a straight line path in thedirection of its axis only and being oper-' atively connected betweensaid frame and a predetermined point on said lever for applying alinearly varying force to said lever at a fixed point and at a fixedangle to the lever during movement of said platform, thereby toresiliently resist vertical movement of said platform in a firstdirection with a linearly varying torque and a constant weight todistance gradient; said resilient means applying a linearly varying biasto said lever to create-therewith a moment force about said pivot pointtoresist said vertical movement of the article support platform in saidfirst direction and said stand including means for selectively varyingthe point of application of said bias force to said lever, withoutvarying the preload force of said spring, whereby the moment forceresisting said vertical movement of said platform and the force gradientapplied to said platform are selectively varied.

2. The article supporting stand as defined in claim 1 wherein said meansfor selectively varying the point of application of said bias force tosaid lever includes a first'ca'rriage mounted for movement along saidlever and being operatively connected to said resilient means.

3. The article supporting stand as defined in claim 2 wherein said meansfor selectively varying the point of application of said bias force tosaid lever further includes means for selectively varying the locationof said first carriage on said lever.

4. The article supporting stand as defined in claim 3 wherein said meansfor varying the location of said first carriage on said lever comprisesa second carriage mounted in said frame for selective vertical movementand means operatively interconnecting said first and second carriagesfor moving said first carriage along said lever in response to verticalmovement of said second carriage, said last mentioned means permittingpivotal movement of said lever in response to vertical movement of saidplatform and holding said first carriage in a relatively fixed position,during said pivotal movement whereby the point of application of saidbias force to said lever remains substantially constant during pivotalmovement of said lever.

5. The article supporting stand as defined in claim 4 wherein saidresilient means includes a spring, a flexible cable connected at one endto said spring and at its opposite end to said second carriage and aplurality of rollers defining a path of travel for said last mentionedcable, including a first roller mounted on said first carriage and asecond roller mounted on said second carriage, said last mentioned cablebeing guided from its point of connection with said second carriage oversaid roller and then over said second roller to its point of connectionwith said spring whereby the initial load on said spring is uneffectedby the position of said second carriage.

6. The article supporting stand as defined in claim 5 wherein said meansfor operatively interconnecting said first and second carriages includesa flexible reference cable operatively connected at its opposite ends tosaid first and second carriages and at least two rollers defining a pathof travel for said reference cable and including a first roller mountedfor rotation about said pivot point and a second roller mounted on saidlever, at a position wherein said first carriage is between it and saidsecond pivot point, said reference cable being guided from its point ofconnection with said first carriage over said second roller and thenceover said first roller to said second carriage, whereby said firstcarriage moves along said lever in response to vertical movement of saidsecond carriage, a distance equal to the distance moved by said secondcarriage.

7. The article supporting stand as defined in claim 6 wherein said meansfor causing said lever to pivot comprises at least one cable operativelyassociated with said lever and connected at one end to said platform andat its other to said frame.

8. The article supporting stand as defined in claim 7 wherein said meansfor causing said lever to pivot comprises at least two. flexible cablesrespectively connected at one end to a common point on said frame andconnected at their opposite ends to opposite sides of said platform anda plurality of guide rollers including a pair of rollers mounted on saidlever for respectively engaging and reversing the direction of said lastmentioned cables between their ends whereby, for every two inches ofvertical movement of said platform, said rollers move with said lever atmost only'one inch, as said lever pivots about its pivot point.

9. The article supporting stand as defined in claim 8 wherein saidplatform is mounted in said frame adjacent only one edge thereof andextends from said frame as a cantilever and said lever is mounted insaid frame for pivotal movement in a vertical plane located beyondsaidone edge of said platform to permit said platform to move verticallywith respect thereto.

10. An article support stand comprising a generally vertically extendingframe, an article support platform mounted at one end in said frame forreciprocal vertical movement between upper and lower positions on saidframe and extending horizontally outward of each frame as a cantilever,and means for resiliently supporting said platform on said frame and forbiasing said platform towards its uppermost position, and meansincluding a lever pivotally mounted in said frame at a fixed pivot pointfor pivotal movement in a vertical plane, a first pair of flexiblecables respectively connected at one end to a common point on said frameand connected at their opposite ends to opposite sides of said platformadjacent said one end thereof, a plurality of guide rollers mounted insaid frame over which said first pair of cables are guided between theirends including a pair of rollers mounted on said lever for respectivelyengaging and reversing the direction of said cables between their endswhereby vertical movement of said platform between its upper andlowermost positions causes said lever to pivot about its pivot point;means for applying a biasing force to said lever to create therewith amoment force about said pivot point which resists downward movement ofsaid platform and normally urges said platform towards its upperposition, said biasing means including a first carriage mounted formovement along said lever, and a spring operatively connected to saidcarriage for applying said bias force to said lever in a predetermineddirection to resist downward movement of said platform; and means, forselectively varying the location of said first carriage along saidlever, thereby to vary selectively the point of application of saidbiasing force to said lever; said means for varying the location of saidfirst carriage on said lever comprising a second carriage mounted insaid frame for selective vertical movement, a flexible reference cableoperatively connected at its opposite ends to said first and secondcarriages, a first roller mountedin said frame below said secondcarriage, a second roller mounted for rotation about said pivot pointand a third roller mounted on said lever at a position wherein saidfirst carriage is between said pivot point and said third roller, saidreference cable being guided from its point of connection with saidsecond carriage sequentially over said first through third rollers toits point of connection with said first carriage whereby said firstcarriage moves along said lever, in response to vertical movement ofsaid second carriage, a distance equal to the distance moved by saidsecond carriage.

11. The article supporting stand as defined in claim 10 including aflexible cable operatively connected at its opposite ends to said springand said second carriage, a first guide roller mounted on said firstcarriage, a second guide roller mounted on said second carriage, and athird guide roller mounted in said frame, below said second carriage, invertical alignment with said second guide roller, said last mentionedflexible cable being guided from its point of connection with saidsecond carriage over said guide roller on said first carriage,'thenceover the guide'on said second carriage and the third guide roller onsaid frame to its point of connection with said spring, whereby saidspring is operatively connected to said first carriage to apply saidbias force to said lever and said bias force is substantially uneffectedby the position of said first and second carriages.

12. The article support stand as defined in claim 11 including athreaded actuating rod mounted in said frame and threadedly engaged withsaid second carriage, whereby rotation of said rod selectively variesthe vertical position of said second carriage in said frame, thereby tovary the location of said first carriage on said lever.

13. An article support stand comprising, a frame, a generally horizontalarticle support platform mounted on said frame for reciprocal movementbetween upper and lower positions on said frame, and means forresiliently supporting said platform on said frame and for biasing saidplatform towards its uppermost position, said means including a leverpivotally mounted in said frame, means operatively connected betweensaid lever, frame and platform for causing said lever to pivot, meansfor applying a biasing force to said lever to create therewith a momentforce which resists downward movement of said platform and normallyurges said platform towards its upper position, said biasing meansincluding a first carriage mounted for movement along said lever and aspring operatively connected between said frame and said first carriageto apply said biasing force to said lever in a predetermined directionto resist downward movement of said platform; a second carriage mountedin said frame for selective vertical movement with respect thereto, andmeans, operatively interconnecting said first and second carriages andsaid spring, for varying the location of said first carriage on saidlever in response to vertical movement of said second carriage and forholding said first carriage in a fixed position on the lever duringpivotal movement thereof, without effecting the bias force applied tosaid lever, whereby the moment force resisting vertical movement of saidplatform may be selectively varied by selected movement of said secondcarriage.

14. The article support stand as defined in claim 13 wherein said meansfor varying the location of said first carriage on said lever includes aflexible reference cable operatively connected at its opposite ends tosaid first and second carriages, a first roller mounted in said framebelow said second carriage, a second roller mounted for rotation aboutthe pivotal axis of said lever and a third roller mounted on said leverat a position wherein said first carriage is between said pivot pointand said third roller, said reference cable being guided from its pointof connection with said second carriage sequentially over said firstthrough third rollers to its point of connection with said firstcarriage whereby said first carriage moves along said lever, in responseto vertical movement of said second carriage, a distance equal to thedistance moved by said second carriage; and a second flexible cableoperatively con nected at its opposite ends to said spring and saidsecond carriage, a first guide roller mounted on said first carriage, asecond guide roller mounted on said second carriage, and a third guideroller mounted in said frame below said second carriage in verticalalignment with said second guide roller, said last mentioned flexiblecable being guided from its point of connection with said secondcarriage over said guide roller on said first carriage and thence overthe guide roller on said second carriage and the third guide roller onsaid frame to its point of connection with said spring, whereby saidspring is operatively connected to said first carriage to apply saidbias force to said lever and said bias force is substantially uneffectedby the position of said first and second carriages.

15. The article support stand as defined in claim 14 including athreaded actuating rod mounted in said frame and threadedly engaged withsaid second carriage, whereby rotation of said rod selectively variesthe vertical position of said second carriage in'said frame, thereby tovary the location of said first carriage

1. An article support stand comprising, a frame, a generally horizontalarticle support platform mounted on said frame for reciprocal verticalmovement, said means including a lever pivotally mounted in said frameat a fixed pivot point, means operatively connected between said lever,frame and platform, for causing said lever to pivot about said fixedpivot point during vertical movement of said platform and resilientmeans mounted in said frame for extension is a straight line path in thedirection of its axis only and being operatively connected between saidframe and a predetermined point on said lever for applying a linearlyvarying force to said lever at a fixed point and at a fixed angle to thelever during movement of said platform, thereby to resiliently resistvertical movement of said platform in a first direction with a linearlyvarying torque and a constant weight to distance gradient; saidresilient means applying a linearly varying bias to said lever to createtherewith a moment force about said pivot point to resist said verticalmovement of the article support platform in said first direction andsaid stand including means for selectively varying the point ofapplication of said bias force to said lever, without varying thepreload force of said spring, whereby the moment force resisting saidvertical movement of said platform and the force gradient applied tosaid platform are selectively varied.
 2. The article supporting stand asdefined in claim 1 wherein said means for selectively varying the pointof application of said bias force to said lever includes a firstcarriage mounted for movement along said lever and being operativelyconnected to said resilient means.
 3. The article supporting stand asdefined in claim 2 wherein said means for selectively varying the pointof application of said bias force to said lever further includes meansfor selectively varying the location of said first carriage on saidlever.
 4. The article supporting stand as defined in claim 3 whereinsaid means for varying the location of said first carriage on said levercomprises a second carriage mounted in said frame for selective verticalmovement and means operatively interconnecting said first and secondcarriages for moving said first carriage along said lever in response tovertical movement of said second carriage, said last mentioned meanspermitting pivotal movement of said lever in response to verticalmovement of said platform and holding said first carriage in arelatively fixed position, during said pivotal movement whereby thepoint of application of said bias force to said lever remainssubstantially constant during pivotal movement of said lever.
 5. Thearticle supporting stand as defined in claim 4 wherein said resilientmeans includes a spring, a flexible cable connected at one end to saidspring and at its opposite end to said second carriage and a pluralityof rollers defining a path of travel for said last mentioned cable,including a first roller mounted on said first carriage and a secondroller mounted on said second carriage, said last mentioned cable beingguided from its point of connection with said second carriage over saidroller and then over said second roller to its point of connection withsaid spring whereby the initial load on said spring is uneffected by theposition of said second carriage.
 6. The article supporting stand asdefined in claim 5 wherein said means for operatively interconnectingsaid first and second carriages includes a flexible reference cableoperatively connected at its opposite ends to said first and secondcarriages and at least two rollers defining a path of travel for saidreference cable and including a first roller mounted for rotation aboutsaid pivot point and a second roller mounted on said lever, at aposition wherein said first carriage is between it and said second pivotpoint, said reference cable being guided from its point of connectionwith said first carriage over said second roller and thence over saidfirst roller to said second carriage, whereby said first carriage movesalong said lever in response to vertical movement of said secondcarriage, a distance equal to the distance moved by said secondcarriage.
 7. The article supporting stand as defined in claim 6 whereinsaid means for causing said lever to pivot comprises at least one cableoperatively associated with said lever and connected at one end to saidplatform and at its other to said frame.
 8. The article supporting standas defined in claim 7 wherein said means for causing said lever to pivotcomprises at least two flexible cables respectively connected at one endto a common point on said frame and connected at their opposite ends toopposite sides of said platform and a plurality of guide rollersincluding a pair of rollers mounted on said lever for respectivelyengaging and reversing the direction of said last mentioned cablesbetween their ends whereby, for every two inches of vertical movement ofsaid platform, said rollers move with said lever at most only one inch,as said lever pivots about its pivot point.
 9. The arTicle supportingstand as defined in claim 8 wherein said platform is mounted in saidframe adjacent only one edge thereof and extends from said frame as acantilever and said lever is mounted in said frame for pivotal movementin a vertical plane located beyond said one edge of said platform topermit said platform to move vertically with respect thereto.
 10. Anarticle support stand comprising a generally vertically extending frame,an article support platform mounted at one end in said frame forreciprocal vertical movement between upper and lower positions on saidframe and extending horizontally outward of each frame as a cantilever,and means for resiliently supporting said platform on said frame and forbiasing said platform towards its uppermost position, and meansincluding a lever pivotally mounted in said frame at a fixed pivot pointfor pivotal movement in a vertical plane, a first pair of flexiblecables respectively connected at one end to a common point on said frameand connected at their opposite ends to opposite sides of said platformadjacent said one end thereof, a plurality of guide rollers mounted insaid frame over which said first pair of cables are guided between theirends including a pair of rollers mounted on said lever for respectivelyengaging and reversing the direction of said cables between their endswhereby vertical movement of said platform between its upper andlowermost positions causes said lever to pivot about its pivot point;means for applying a biasing force to said lever to create therewith amoment force about said pivot point which resists downward movement ofsaid platform and normally urges said platform towards its upperposition, said biasing means including a first carriage mounted formovement along said lever, and a spring operatively connected to saidcarriage for applying said bias force to said lever in a predetermineddirection to resist downward movement of said platform; and means forselectively varying the location of said first carriage along saidlever, thereby to vary selectively the point of application of saidbiasing force to said lever; said means for varying the location of saidfirst carriage on said lever comprising a second carriage mounted insaid frame for selective vertical movement, a flexible reference cableoperatively connected at its opposite ends to said first and secondcarriages, a first roller mounted in said frame below said secondcarriage, a second roller mounted for rotation about said pivot pointand a third roller mounted on said lever at a position wherein saidfirst carriage is between said pivot point and said third roller, saidreference cable being guided from its point of connection with saidsecond carriage sequentially over said first through third rollers toits point of connection with said first carriage whereby said firstcarriage moves along said lever, in response to vertical movement ofsaid second carriage, a distance equal to the distance moved by saidsecond carriage.
 11. The article supporting stand as defined in claim 10including a flexible cable operatively connected at its opposite ends tosaid spring and said second carriage, a first guide roller mounted onsaid first carriage, a second guide roller mounted on said secondcarriage, and a third guide roller mounted in said frame, below saidsecond carriage, in vertical alignment with said second guide roller,said last mentioned flexible cable being guided from its point ofconnection with said second carriage over said guide roller on saidfirst carriage, thence over the guide on said second carriage and thethird guide roller on said frame to its point of connection with saidspring, whereby said spring is operatively connected to said firstcarriage to apply said bias force to said lever and said bias force issubstantially uneffected by the position of said first and secondcarriages.
 12. The article support stand as defined in claim 11including a threaded actuating rod mounted in said frame and threAdedlyengaged with said second carriage, whereby rotation of said rodselectively varies the vertical position of said second carriage in saidframe, thereby to vary the location of said first carriage on saidlever.
 13. An article support stand comprising, a frame, a generallyhorizontal article support platform mounted on said frame for reciprocalmovement between upper and lower positions on said frame, and means forresiliently supporting said platform on said frame and for biasing saidplatform towards its uppermost position, said means including a leverpivotally mounted in said frame, means operatively connected betweensaid lever, frame and platform for causing said lever to pivot, meansfor applying a biasing force to said lever to create therewith a momentforce which resists downward movement of said platform and normallyurges said platform towards its upper position, said biasing meansincluding a first carriage mounted for movement along said lever and aspring operatively connected between said frame and said first carriageto apply said biasing force to said lever in a predetermined directionto resist downward movement of said platform; a second carriage mountedin said frame for selective vertical movement with respect thereto, andmeans, operatively interconnecting said first and second carriages andsaid spring, for varying the location of said first carriage on saidlever in response to vertical movement of said second carriage and forholding said first carriage in a fixed position on the lever duringpivotal movement thereof, without effecting the bias force applied tosaid lever, whereby the moment force resisting vertical movement of saidplatform may be selectively varied by selected movement of said secondcarriage.
 14. The article support stand as defined in claim 13 whereinsaid means for varying the location of said first carriage on said leverincludes a flexible reference cable operatively connected at itsopposite ends to said first and second carriages, a first roller mountedin said frame below said second carriage, a second roller mounted forrotation about the pivotal axis of said lever and a third roller mountedon said lever at a position wherein said first carriage is between saidpivot point and said third roller, said reference cable being guidedfrom its point of connection with said second carriage sequentially oversaid first through third rollers to its point of connection with saidfirst carriage whereby said first carriage moves along said lever, inresponse to vertical movement of said second carriage, a distance equalto the distance moved by said second carriage; and a second flexiblecable operatively connected at its opposite ends to said spring and saidsecond carriage, a first guide roller mounted on said first carriage, asecond guide roller mounted on said second carriage, and a third guideroller mounted in said frame below said second carriage in verticalalignment with said second guide roller, said last mentioned flexiblecable being guided from its point of connection with said secondcarriage over said guide roller on said first carriage and thence overthe guide roller on said second carriage and the third guide roller onsaid frame to its point of connection with said spring, whereby saidspring is operatively connected to said first carriage to apply saidbias force to said lever and said bias force is substantially uneffectedby the position of said first and second carriages.
 15. The articlesupport stand as defined in claim 14 including a threaded actuating rodmounted in said frame and threadedly engaged with said second carriage,whereby rotation of said rod selectively varies the vertical position ofsaid second carriage in said frame, thereby to vary the location of saidfirst carriage on said lever.